1. Field of the Invention
The invention is directed to a new hydrogen engine and to a process to eliminate abnormal combustion in a hydrogen fueled engine.
Hydrogen combustion can provide excellent energy efficiency and can produce combustion gases having very low NOx content. However, when used as the primary fuel in a conventional internal combustion engine, it experiences abnormal or premature combustion, making it difficult to control and to use as a primary fuel.
2. Description of the Prior Art
Several patents disclose hydrogen as a fuel. For example, Quigley, Jr. (U.S. Pat. No. 3,471,274) discloses a hydrogen combustion engine that utilizes a vacuum exhaust pump to remove products of combustion. A vacuum exhaust pump is connected to an exhaust pipe to remove combustion products when the exhaust ports are uncovered by the piston.
Stowe (U.S. Pat. No. 5,231,954) discloses a hydrogen/oxygen fuel cell for supplementing gasoline, which is said to improve thermal efficiency and reduce emissions. Atmospheric air and accumulated crankcase gases are swept through the crankcase through a crankcase vent hose tube which forms a part of a positive crankcase ventilation (PCV) system.
In previous studies (Ernest, R. P., "A Unique Cooling Approach Makes Aluminum Alloy Cylinder Heads Cost Effective," Ford Motor Company, SAE Paper No. 770832, 1977), it was noted that the principal obstacle to heat transfer in an aluminum cylinder head was the aluminum-coolant interface at locations where low flow rates of coolant and film boiling can occur. The incidence of film boiling on the exhaust ports in the water jacket has been found to coincide with flashback in the engine. This finding is consistent with theoretical analysis and has been noted by others (Withalm, G., and Gelse, W., "The Mercedes-Benz Hydrogen Engine for Application in a Fleet Vehicle," Proceedings of the 6th World Hydrogen Energy Conference, Vienna, Austria, 20-24 Jul. 1986). Since surface ignition is not as large a problem with gasoline-fueled engines as with hydrogen-fueled engines, it has not been necessary, in the past, to carefully design cylinder heads with uniform coolant flow rates. Coolant systems which avoid such nonuniformities in local coolant flow rate have been developed (Ernest, 1977; Finlay, I. C., Gallacher, G. R., Biddulph, T. W., and Marshall, R. A., "The Application of Precision Cooling to the Cylinder-Head of a Small, Automotive, Petrol Engine," SAE Paper 880263).
The problem remains, however, that abnormal combustion takes place when the primary fuel is hydrogen, especially when attempted to be operated at heavy loads for extended periods of time.